Preparation,Doping,Application,Properties Of Tin Dioxide And Titanium Dioxide Nanopowders

In this paper,the performance,preparation and application of nanomaterials were discussed,besides seeking to develop mild or simple new preparation methods to prepare tin dioxide(SnO2)and titanium dioxide(TiO2).Crystalline size-control of SnO2 nanopowders with tunable properties were prepared by HNO3-C2H5OH assisted precipitation method.TiO2 nanopowders were prepared by direct precipitation method.Sn,Fe doped TiO2 nanopowders were prepared by co-precipitation method.The details are summarized as follows:(1)The nucleation and growth of SnO2 nanopowders were controled by varing the amount of HNO3-C2H5OH additives.Pure SnO2 nanopoweders with high crystallinity and small size were obtained without changing the calcination temperature.With the increase of the amount of HNO3-C2H5OH additives,the maximum exothermic heat of the SnO2 precursor at 475?decreased,which effectively suppressed the growth of the SnO2 nanopowders.The thermal behavior of SnO2 precursors,crystal structure,morphology,composition,light absorption,resistivity,gas sensitivity and bulk density and the formation mechanism of SnO2 nanopowders were investigated and analyzed.(2)The composite of a nanocrystalline SnO2 thick film desposited on an Al-doped ZnO ceramic substrate was firstly proposed.The composites were synthesized by direct liquid phase synthesis combined with solid-state reaction routes.The crystal structure,morphology,composition and gas sensitivity of composites were studied and analyzed in detail.Three-dimensional network-like porous microstructure can effectively improve the gas-sensing properties of composites.(3)TiO2 precursors were prepared by direct precipitation method using TiCl4 and NH4OH.The effect of temperature and heating time on TiO2 nanopowders were investigated.The thennal effect,crystal structure,grain size,light absorption and photocatalytic properties of calcinated TiO2 nanopowders were investigated.Elevated temperature can promote grain growth and crystal transformation.The mixture of a small amount of rutile phase with anatase phase could significantly improve the photocatalytic properties of TiO2 nanopowders.When the calcination temperature was 450?,the heating time had no effect on the crystal structure and grain size of TiO2 nanopowders,but the heating time can decrease the Cl content.(4)The effects of Sn doping,Fe doping and Fe/N co-doping on the photocatalytic activity of TiO2 nanopowders prepared by coprecipitation method were investigated.Sn doping and Fe doping can decrease the crystalline size of nanopowders.Sn doping promoted anatase to rutile phase trasformation,while Fe doping inhibited anatase to rutile phase transformation.A small amount of Sn dopant could effectively improve the photocatalytic properties of TiO2 nanopowders.0.3%Fe/N-TiO2-450? nanopowders had the best photocatalytic effect,and the mechanism of Fe/N co-doping on the photocatalytic activity of TiO2 nanopowders was proposed.